1. Field of the Invention
The present invention relates to an apparatus for estimating a slip angle of a wheeled vehicle for control of a suspension system and/or a rear-wheel steering mechanism in a four-wheel steering system.
2. Discussion of the Prior Art
In Japanese Patent Early Publication No. 60-191876, there has been proposed a rear-wheel steering mechanism the operation of which is controlled in accordance with a slip angle of the wheeled vehicle to enhance stability in the steering operation. In the rear-wheel steering mechanism, plural kinds of sensors are provided to detect each steering angle of the front and rear road wheels, a travel speed of the vehicle, a weight of the vehicle and a yaw-rate of the vehicle, and a computer is adapted to solve a condition equation on a basis of input data indicative of the steering angles, travel speed, weight and yaw-rate thereby to estimate a slip angle of the vehicle. The provision of such various kinds of sensors will lower productivity of the steering mechanism, and the time consumption for calculation of the equation will increase because of a large amount of data to be calculated.